High density core memory matrix

ABSTRACT

A high density core memory matrix has cores spaced very close together along longitudinal axes and moderately close along latitudinal axes. The close longitudinal spacing is facilitated by orienting the cores at the maximum acute angle with respect to the longitudinal axis consistent with proper passage of the latitudinal drive lines. Undesirable electrical characteristics and propagation-time delays are minimized by passing the sense and inhibit lines along the extremely compacted longitudinal axis.

United States Patent [1 1 Sell et al.

[ Jan. 16, 1973 [54] HIGH DENSITY CORE MEMORY MATRIX [75] Inventors:Victor L. Sell, Santa Monica; Syed M. S. Alvi, Placentia, both of Calif.

[73] Assignee: Ampex Corporation, Redwood City,

Calif.

[22] Filed: July 26, 1971 21 A pl. No.1 165,477

[52] US. Cl. ..340/l74 M, 340/174 AC, 340/174 CR [51] Int. Cl ..Gllc5/02,Gllc5/06,Gllc 11/06 [58] Field of Search ...340/174 M, 174 MA, 174VA,

340/174 CR, 174 BA [56] References Cited UNITED STATES PATENTS 3,085,3144/l963 Lciching ..340/l 74 M OTHER PUBLICATIONS [BM Technical DisclosureBulletin Vol. 3, No. 1-

June 1960, pg. 45.

IBM Technical Disclosure Bulletin Vol. 3, No. l0,

Mar. i961, pgs. 105-106.

Primary Examiner--James W. Moffitt Att0rney-Robert G. Clay [57] ABSTRACTA high density core memory matrix has cores spaced very close togetheralong longitudinal axes and moderately close along latitudinal axes. Theclose longitudinal spacing is facilitated by orienting the cores at themaximum acute angle with respect to the longitudinal axis consistentwith proper passage of the latitudinal drive lines. Undesirableelectrical characteristics and propagation-time delays are minimized bypassing the sense and inhibit lines along the extremely compactedlongitudinal axis.

18 Claims, 2 Drawing Figures PATENTEDJANISIBB 4Y6; INVENTORS SYEDH.S.ALVI VICTOR L. SELL ATTORNEYS HIGH DENSITY CORE MEMORY MATRIXBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to coincident current magnetic hibiting or separate wires forread half select and write half select on one or both axes. In the2-wire, 2% D arrangements one of the half select lines is simultaneouslyused for sensing and no inhibit line is used.

Regardless of which core or wiring arrangement is used the cores arelocated on centers which are at least spaced one diameter apart in boththe longitudinal and latitudinal directions. The cores are located at anangle of 45 to bisectthe angle between the longitudinal and latitudinalaxes thus permitting diagonal threading of the sense lines to balancethe partial excitation noise signals and obtain mutual cancellation.

SUMMARY OF THE INVENTION An improved high density core arrangement isattained by arranging a matrix of magnetic cores in a double herringbonepattern wherein two adjacent longitudinal rows of cores have the sameorientation to form a similarly oriented pair of rows. Adjacent rowpairs have opposite orientations. The cores are oriented at anonbisecting acute angle greater than 45 with respect to thelongitudinal axis and are greatly compacted, thereby permitting a senseline located along this longitudinal axis to be much shorter.

In one arrangement the cores are located on centers spaced approximatelyone-half diameter apart along the longitudinal axis and approximatelyone diameter apart along the latitudinal axis. The cores are oriented atan angle of 50 with respect to the longitudinal axis to accommodate thisspacing.

This closely packed double herringbone arrangement provides manyadditional advantages. The bit density is doubled and the signalpropagation time is greatly reduced. This is particularly important inlarge memory planes where it is desirable to have a constant access timeregardless of core position. Additional advantages are gained from adecrease in the capacitance between the sense line and the drive linesand a decrease in the self inductance of the sense line. These factors,which are largely dependent upon the length of the sense and drive linesgreatly decrease the amount of disturbance on the sense line as well asthe amount of drive power that is required. Further, the closepositioning of the cores along the longitudinal axes produces atunneling or magnetic shielding effect. The spacing between cores is sosmall that the cores overlap and very little magnetic flux is able toescape the tunnel to couple with an adjacent row. Thus inductivecoupling between wires in adjacent rows may be reduced as much as to 1.

Another advantage of the close spacing technique is manifested as thewires are threaded through the cores during manufacture. A needle isused to thread the various wires through the cores and it frequentlyhappens that the needle point gouges or chips a piece of core materialfrom one of the cores. This results in a defective core which must bereplaced. However, as a result of the close spacing of the cores aneedle is more closely constrained to the path through the core centersand needle damage is substantially reduced.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of theinvention may be had from a consideration of the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a schematic representation of a portion of a core memorymatrix arranged in accordance with the invention;

FIG. 2 is an enlarged, sectional view of a portion of the core memorymatrix shown in FIG. 1, illustrating the preferred angle of orientationand spacing of magnetic cores.

DETAILED DESCRIPTION A high density core memory matrix in accordancewith the invention utilizes a double herringbone pattern with corespositioned on centers less than one diameter apart and oriented at anacute angle greater than 45 with respect to longitudinal axes. The corespacing is particularly compressed along the longitudinal axes and thelength of a sense line is minimized by running it parallel to thelongitudinal axes. Such an arrangement provides substantialmanufacturing and operating advantages.

As shown in FIG. 1, a high density core memory matrix in accordance withthe invention has a substrate 12 with a matrix of magnetic cores 14bonded thereto. The matrix in this example forms a memory plane having16,384 cores with 128 cores in each row and each column. The example ofFIG. 1 uses a 3-wire arrangement with an X or longitudinal drive line16, a Y or latitudinal drive line 18 and a sense-inhibit line 20inductively coupling each core. However, this high density technique isequally applicable to other wiring arrangements such as those having 2or 4 wires coupling each core.

Although cores of any size may be used, in this example the cores 14 arestandard sized 18 mil cores having an outside diameter of 0.0178-inches,an inside diameter of 0.01 17 inches and a width of 0.0042 inches. Theyare positioned in a double herringbone pattern in which two adjacentlongitudinal rows of cores have a similar orientation to form a row pairand the cores of adjacent row pairs have opposite orientations. Minimalspacing along the longitudinal axis is attained by orienting the coresat the maximum angle consistent with threading of the latitudinal drivewire, 18 in this example. Furthermore, to obtain proper noisecancellation the core orientations may be reversed at selected intervalsalong each row pair and the sense-inhibit lines, which extend along therows, may cross from one row in a row pair to the other. Thus, the coresin the lefthand portion of row pair X X which intersect column windingsY Y have an opposite orientation from those in the righthand portionwhich intersect column windings Y Y It will be appreciated that thenumber of core orientation reversals or sense-inhibit line crossoverscan be increased if desired.

In addition to the longitudinal X drive lines a senseinhibit line 20passes through each of the cores in the longitudinal direction. Thissense-inhibit line 20 has two symmetrical halves labeled S-Ia and S-Ibwhich are connected at center tap 22. Each core in each row pair iscoupled to one of the two halves of the sense-inhibit line 20 while thecorresponding cores in the pairing row are inductively coupled to theother half. Thus each core in the matrix is inductively coupled to oneof the two halves of the sense line. The symmetrical arrangement of thesense-inhibit line halves, together with the periodic reversal of thecore orientations and sense-inhibit line crossovers results in acancellation of noise disturbances when the switching of a core is beingsensed.

The center tap 22 is connected to an inhibit wire 24 which in turn isconnected by a switch 26 to a current sink or driver (not shown). Duringa read operation the sense-inhibit line 20 functions as a singlebalanced sense line with the switch 26 open and during a write operationthe sense-inhibit line functions as two parallel inhibit lines with theswitch 26 closed.

It will be appreciated by those skilled in the art that other patterns,spacings and orientations may be employed in accordance with theinvention. For instance, similarly oriented groups of rows may containfour rather than two rows and different sizes of drive and sense wiresmay be used. The use of smaller latitudinal drive lines may permit asomewhat greater angle of orientation, thereby decreasing the threadingaperture," but also enabling a closer spacing along the longitudinalaxes.

Some important factors which affect the spacing of magnetic cores areillustrated in FIG. 2 which shows several cores 14 from the exampleshown in FIG. 1 at the intersection of the drive line pair X X withlatitudinal drive lines Y Y and Y It can be seen that as the two drivewires and the sense-inhibit wire intersect at a core 14 the Y drive linepasses between the X drive line and the sense-inhibit line. This affordsa Y drive line an optimum aperture" as it passes through the cores in acolumn.

As shown in FIG. 1, the 18 mil cores 14 used in this example are locatedon center points which are spaced a distance A 0.0167 inch apart alongthe latitudinal axes between rows which are similar oriented and form arow pair. Between rows which are oppositely oriented the spacing is B0.0181 inch. The longitudinal spacing between the center points is C0.010 inch between cores which are similarly oriented and 0.0181 inch atthe crossover point of the sense-inhibit line between drive lines Y. andY In this example the X and Y lines have diameters of 0.0027 inch andthe sense-inhibit line has a diameter of 0.0029 inch.

For 18 mil cores care must be taken when determining core spacing tomaintain a clearance of about 0.0018 inch between cores and betweencores and wires. Otherwise vibrational forces might cause destructivecontacts which chip or otherwise damage the cores. Particularly criticalare the distances between the outside diameters of adjacent cores andbetween a core and an adjacent Y drive line as illustrated in FIG. 2 bydistances 32 and 34 respectively.

As a result of the close core spacing of this arrangement the magneticcores provide a tunneling or shielding effect which greatly reducesmagnetic coupling between wires in adjacent rows. For instance, intrying to visualize vertical paths connecting drive line X with aportion of the sense-inhibit line in row X it can be seen that thesevertical paths are substantially limited to the apertures through whichthe Y drive lines pass. This shielding reduces inductive couplingbetween rows by a factor of 10 or more.

The constraints which apply to the orientation of a magnetic core areillustrated in conjunction with the core which appears at theintersection of drive lines X and Y in FIG. 2. As shown therein the coreis oriented at an angle a with respect to its longitudinal axis and hasa vertical opening or aperture 40 with a width D for receiving driveline Y The core has an outside diameter D an inside diameter D,- and awidth W.

From the standpoint of increasing core density along the longitudinalaxis and decreasing the length of the sense-inhibit line it is desirableto orient the cores as nearly vertically as possible. This isillustrated by the spacing distance 34, as the core at the intersectionof drive lines X and Y is rotated clockwise to a slightly more verticalorientation distance 34 increases. thus permitting a closer spacing.However, manufacturing considerations require that cores be able toreceive a Y drive line without bending the line or the needle used tothread it. If there is not a straight path or aperture through a columnof cores there will be needle damage as the cores are threaded. Toprovide adequate clearance the width D of the aperture 40 should benearly double the diameter of the latitudinal drive line Y By extendingthe line of the lower edge of the inside diameter 42 of the core 14 tomeet the righthand edge of the window 40, a right triangle havingvertices 44, 45, 46 is formed. It can be seen that the angle at vertex45 is the angle at vertex 44 is 0 90 a and the angle at vertex 46 is a.It can be further seen from this arrangement that:

Applying this formula to the dimensions used in the example shown inFIG. 1 where W=0.0042, D,= 0.0117, and a 50, it can be determined that D0.00428 inch. This is slightly less than twice the 0.0027 inch diameterof the drive line Y as required. In contrast, the 45 orientation forpresently known arrangements would result in unnecessarily large windowsand much less dense core spacings.

In addition to the advantages of increased bit density and decreasedneedle damage, there are substantial electrical advantages to be gainedfrom arrangements in accordance with this inventiOn. The capacitivecoupling between the parallel sense-inhibit and X drive lines is giventhe formula 1rE1 cash- (d/a) 4 where CAP capacitance, E permittivity ofthe dielectric between the two lines, 1 length of the parallel line inmeters, d separation between the two lines in meters and a diameter ofthe wires in meters.

where N is the number of cores in a longitudinal, row, N,,,,, is thenumber of cores in a latitudinal column, A is the latitudinal spacingbetween core center points in similarly oriented rows, B is thelatitudinal spacing between core center points in oppositely orientedrows, and C is the longitudinal spacing between cores. Because (N l) (C)is normally much greater than A+B the first portion of equation (5)predominates. Thus the length of the sense line is nearly proportionalto C, the spacing between cores. For this reason the length of the senseline is nearly halved as compared with previously known doubleherringbone arrangements. As compared to previously. known arrangementsusing a diagonally oriented sense line the reduction in sense linelength is even greater. The sense line length for these arrangements hasan additional factor of V2 because it connects diagonali rather thanadjacent cores. This results in a shortening of the sense line length byapproximately 2 V2as com-; pared to diagonal sense lines. It can thus beseen from equation (4) that the present arrangement reducesi capacitivecoupling by nearly 2 and 2 V2 over previ-i ously known arrangements.

Furthermore, signal delay, 7 is proportional to V L(CAP)l where L is theinductance of the line in hen ties/meter and equals [.L/IT cosh (d/a)1,and where p. is

i the permeability of the dielectric medium. For the arrangement of FIG.1 as compared to a similar double herringbone pattern but with coreslocated on centers spaced one diameter apart, it has been shown thatcapacitance can be reduced by a factor of 2.75, in-. ductance by afactor of 1.46, and signal delay by a factor of 2.0.

Although there has been described above a specific arrangement of a highdensity core memory matrix in accordance with the invention for thepurpose of illustrating the manner in which the invention may be used toadvantage, it will be appreciated that the invention is not limitedthereto. Accordingly, any and all modifications, variations orequivalent arrangements which may occur to those skilled in the artshould be considered to be within the scope of the invention. What isclaimed is: 1. A core memory comprising: a plurality of magnetic coresdisposed along a lon-' gitudinal axis to form a row of cores similarlyoriented at an acute angle substantially greater. than 45 with respectto the longitudinal axis, said cores being positioned about centerpoints having a spacing between them less than the outside diameter ofcore;

means for selectively switching the magnetic state of a core; and

means for detecting the switching of a core.

2. The invention as set forth in claim 1 above, wherein said detectingmeans is a sense wire extending along the longitudinal axis andinductively coupling all; of the cores in the row.

3. The invention as set forth H6551 i above; wherein the center pointshave a spacing of substantially less than the outside diameter of a corealong the longitudinal axis.

4. The invention as set forth in claim 1 above, wherein the cores havean outside diameter of approximately 0.018 inch and the center pointshave a spacing of approximately 0.010 inch along the longitudinal axis.

5. A core memory matrix comprising:

a plurality of magnetic cores having two stable states and arranged inrows along longitudinal axes and columns along latitudinal axes, eachrow having at least one group of a plurality of adjacent cores which aresimilarly oriented at an acute angle greater than 45 with respect to thelongitudinal axis of the row and which are spaced about center pointsseparated by substantially less than outside diameter of a core alongthe longitudinal axis of the row;

means for switching a selected core from one stable state to another;and

means for detecting the switching of a core.

6. The invention as set forth in claim 5 above, wherein the switchingmeans includes a plurality of column drive lines, each inductivelycoupling all of the cores in a column and a plurality of row drivelines, each inductively coupling all of the cores in a row; and whereinthe detecting means includes at least one. sense line positionedparallel to the row drive lines and inductively coupling at least aportion of the cores in at least one row.

7. A core memory matrix comprising a plurality of magnetic coresarranged in a double herringbone pattern having latitudinal andlongitudinal axes, said cores being positioned about center pointshaving a spacing of substantially less than an outside core diameterbetween them along the longitudinal axes.

8. The invention as set forth in claim 7 above, further comprisinglatitudinal drive means inductively coupling each core along alatitudinal axis, longitudinal drive means inductively coupling eachcore along a longitudinal axis and sense means inductively coupling atleast a plurality of the cores along a longitudinal axis.

9. A magnetic core memory matrix comprising:

a plurality of cores having X and Y axis positions, each of said coresbeing disposed at an acute angle substantially greater than 45 withrespect to the X axis; and

X and Y drive wires disposed orthogonally through said matrix with one Xand Y wire coupling each different one of said cores, said cores havingdifferent spacings along the X and Y axes and having greater densityalong the X axis.

10. The invention as set forth in claim 9 above further including asense wire disposed parallel to the X-axis and coupling said cores.

1 l. A high density core memory matrix comprising:

a substrate;

a plurality of magnetic cores positioned on the substrate in a doubleherringbone pattern with rows of cores defining longitudinal axes andcolumns of cores defining latitudinal axes, the cores being oriented atan acute angle greater than 45 with respect to the longitudinal axes andpositioned about centers having a spacing of substantially less than theoutside diameter of a core between them along the longitudinal axis;

latitudinal drive means inductively coupled to each core for providingeach core in a selected column a partial select current;

longitudinal drive means inductively coupled to each core for providingeach core in a selected row a partial select current, the combinedcolumn and row partial select currents being sufficient to.

switch a core common to the selected row and column; and

means for sensing the switching of a core.

12. The invention as set forth in claim 11 above, wherein said cores arepositioned on centers spaced substantially one-half outside diameterapart along the longitudinal axes and one diameter apart along thelatitudinal axes.

13. The invention as set forth in claim 12 above, wherein said cores areoriented at an angle of 50 and have an outside diameter of 0.0178 inch.

14. The invention as set forth in claim 11 above, wherein saidlatitudinal drive means comprises one wire for each column of coreshaving a diameter approximately D, wherein the cores have an insidediameter D, and a width W and wherein the approximate orientation angle,a, of the cores is defined by the equation w a? We a=8.lsm

W2 TH 15. A core memory comprising:

a plurality of magnetic cores disposed along a plurality of pairs oflongitudinal axes to form row pairs, said cores being oriented at anacute angle substantially greater than 45 with respect to thelongitudinal axes with all cores in a row pair being similarly orientedand cores in adjacent row pairs being oppositely oriented;

a plurality of longitudinal row drive lines, each extending along thelongitudinal axis of one row and inductively coupling each core in therow;

a plurality of latitudinal drive lines extending perpendicular to thelongitudinal drive lines, each inductively coupling at least one core ineach row; and

' means extending along the longitudinal axis of at least one row andinductively coupling all of the cores in the row for selectively sensingand inhibiting the switching of inductively coupled cores.

16. A core memory plane comprising:

a substrate;

a plurality of magnetic cores disposed on one side of the substrate andarranged in rows defining longitudinal axes and columns defininglatitudinal axes, each row having at least one group of cores similarlyoriented at an acute angle substantially greater than 45 with respect toits longitudinal axis, the rows being grouped into pairs of adjacentrows having cores similarly oriented, the cores of adjacent pairs beingoppositely oriented;

latitudinal drive means inductively coupling a half select current toall of the cores of a selected column;

longitudinal drive means inductively coupling a half select current toall of the cores of a selected row;

a sense line extending along the rows of cores and inductively couplingeach core in the plane.

17. A core memory comprising: a plurality of magnetlc cores disposedalong a longitudinal axis to form a row of cores similarly oriented atan acute angle greater than 47 with respect to the longitudinal axis,said cores being positioned about center points having a spacing betweenthem less than the outside diameter of a core;

means for selectively switching the magnetic state of a core; and

means for detecting the switching of a core.

18. A core memory matrix comprising:

a plurality of magnetic cores having two stable states and arranged inrows along longitudinal axes and columns along latitudinal axes, eachrow having at least one group of a plurality of adjacent cores which aresimilarly oriented and which are spaced about center points separated byless than percent of the outside diameter of a core along thelongitudinal axis of the row;

means for switching a selected core from one stable state to another;and

means for detecting the switching of a core.

Disclaimer 3,711,839.-V0t01" L. Sell, Santa Monica, and Syed M. 5. Alan,Placentia, Calif. HIGH DENSITY CORE MEMORY MATRIX. Patent dated J an.16, 1973. Disclaimer filed Nov. 7 197 3, by the assignee, Ampew[Official Gazette Februawy 5, 1.974]

1. A core memory comprising: a plurality of magnetic cores disposedalong a longitudinal axis to form a row of cores similarly oriented atan acute angle substantially greater than 45* with respect to thelongitudinal axis, said cores being positioned about center pointshaving a spacing between them less than the outside diameter of core;means for selectively switching the magnetic state of a core; and meansfor detecting the switching of a core.
 2. The invention as set forth inclaim 1 above, wherein said detecting means is a sense wire extendingalong the longitudinal axis and inductively coupling all of the cores inthe row.
 3. The invention as set forth in claim 1 above, wherein thecenter points have a spacing of substantially less than the outsidediameter of a core along the longitudinal axis.
 4. The invention as setforth in claim 1 above, wherein the cores have an outside diameter ofapproximately 0.018 inch and the center points have a spacing ofapproximately 0.010 inch along the longitudinal axis.
 5. A core memorymatrix comprising: a plurality of magnetic cores having two stablestates and arranged in rows along longitudinal axes and columns alonglatitudinal axes, each row having at least one group of a plurality ofadjacent cores which are similarly oriented at an acute angle greaterthan 45* with respect to the longitudinal axis of the row and which arespaced about center points separated by substantially less than outsidediameter of a core along the longitudinal axis of the row; means forswitching a selected core from one stable state to another; and meansfor detecting the switching of a core.
 6. The invention as set forth inclaim 5 above, wherein the switching means includes a plurality ofcolumn drive lines, each inductively coupling all of the cores in acolumn and a plurality of row drive lines, each inductively coupling allof the cores in a row; and wherein the detecting means includes at leastone sense line positioned parallel to the row drive lines andinductively coupling at least a portion of the cores in at least onerow.
 7. A core memory matrix comprising a plurality of magnetic coresarranged in a double herringbone pattern having latitudinal andlongitudinal axes, said cores being positioned about center pointshaving a spacing of substantially less than an outside core diameterbetween them along the longitudinal axes.
 8. The invention as set forthin claim 7 above, further compRising latitudinal drive means inductivelycoupling each core along a latitudinal axis, longitudinal drive meansinductively coupling each core along a longitudinal axis and sense meansinductively coupling at least a plurality of the cores along alongitudinal axis.
 9. A magnetic core memory matrix comprising: aplurality of cores having X and Y axis positions, each of said coresbeing disposed at an acute angle substantially greater than 45* withrespect to the X axis; and X and Y drive wires disposed orthogonallythrough said matrix with one X and Y wire coupling each different one ofsaid cores, said cores having different spacings along the X and Y axesand having greater density along the X axis.
 10. The invention as setforth in claim 9 above further including a sense wire disposed parallelto the X-axis and coupling said cores.
 11. A high density core memorymatrix comprising: a substrate; a plurality of magnetic cores positionedon the substrate in a double herringbone pattern with rows of coresdefining longitudinal axes and columns of cores defining latitudinalaxes, the cores being oriented at an acute angle greater than 45* withrespect to the longitudinal axes and positioned about centers having aspacing of substantially less than the outside diameter of a corebetween them along the longitudinal axis; latitudinal drive meansinductively coupled to each core for providing each core in a selectedcolumn a partial select current; longitudinal drive means inductivelycoupled to each core for providing each core in a selected row a partialselect current, the combined column and row partial select currentsbeing sufficient to switch a core common to the selected row and column;and means for sensing the switching of a core.
 12. The invention as setforth in claim 11 above, wherein said cores are positioned on centersspaced substantially one-half outside diameter apart along thelongitudinal axes and one diameter apart along the latitudinal axes. 13.The invention as set forth in claim 12 above, wherein said cores areoriented at an angle of 50* and have an outside diameter of 0.0178 inch.14. The invention as set forth in claim 11 above, wherein saidlatitudinal drive means comprises one wire for each column of coreshaving a diameter approximately 1/2 D, wherein the cores have an insidediameter Di and a width W and wherein the approximate orientation angle,Alpha , of the cores is defined by the equation
 15. A core memorycomprising: a plurality of magnetic cores disposed along a plurality ofpairs of longitudinal axes to form row pairs, said cores being orientedat an acute angle substantially greater than 45* with respect to thelongitudinal axes with all cores in a row pair being similarly orientedand cores in adjacent row pairs being oppositely oriented; a pluralityof longitudinal row drive lines, each extending along the longitudinalaxis of one row and inductively coupling each core in the row; aplurality of latitudinal drive lines extending perpendicular to thelongitudinal drive lines, each inductively coupling at least one core ineach row; and means extending along the longitudinal axis of at leastone row and inductively coupling all of the cores in the row forselectively sensing and inhibiting the switching of inductively coupledcores.
 16. A core memory plane comprising: a substrate; a plurality ofmagnetic cores disposed on one side of the substrate and arranged inrows defining longitudinal axes and columns defining latitudinal axes,each row having at least one group of cores similarly oriented at anacute angle substantially greater than 45* with respect to itslongitudinal axis, the rows being grouped into pairs of adjacent rowshaving cores similarly oriented, the cores of adjacent pairs beingoppositely oriented; latitudinal drive means indUctively coupling a halfselect current to all of the cores of a selected column; longitudinaldrive means inductively coupling a half select current to all of thecores of a selected row; a sense line extending along the rows of coresand inductively coupling each core in the plane.
 17. A core memorycomprising: a plurality of magnetic cores disposed along a longitudinalaxis to form a row of cores similarly oriented at an acute angle greaterthan 47* with respect to the longitudinal axis, said cores beingpositioned about center points having a spacing between them less thanthe outside diameter of a core; means for selectively switching themagnetic state of a core; and means for detecting the switching of acore.
 18. A core memory matrix comprising: a plurality of magnetic coreshaving two stable states and arranged in rows along longitudinal axesand columns along latitudinal axes, each row having at least one groupof a plurality of adjacent cores which are similarly oriented and whichare spaced about center points separated by less than 90 percent of theoutside diameter of a core along the longitudinal axis of the row; meansfor switching a selected core from one stable state to another; andmeans for detecting the switching of a core.